Lift systems and methods for supporting cargo on a vehicle

ABSTRACT

A lift system for supporting cargo on a vehicle comprising a vehicle frame, the lift system comprises a cargo platform assembly and a displacement system. Operation of a drive system causes axial rotation of at least one drive axle. Axial rotation of at least one drive axle causes at least one drive link assembly to pivot about a drive axle axis. Pivoting of the at least one drive link assembly about the drive axle axis displaces the cargo platform between a stowed configuration and a lowered configuration. First and second distal axes are forward of the drive axle axis when the lift system is in the stowed configuration and rearward of the drive axle axis when the lift system is in the lowered configuration.

RELATED APPLICATIONS

This application (Attorney's Ref. No. P219982) is a continuation of U.S.patent application Ser. No. 16/393,884 filed Apr. 24, 2019, currentlypending.

U.S. patent application Ser. No. 16/393,884 is a continuation of U.S.patent application Ser. No. 15/458,576 filed Mar. 14, 2017, now U.S.Pat. No. 10,272,816, which issued on Apr. 30, 2019.

The contents of all related applications are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to systems and methods for lifting cargoand, in particular, to vehicle mounted lift systems and methods forcargo such as a secondary vehicle.

BACKGROUND

It is common to use a vehicle to transport heavy loads. It is alsocommon to use a primary vehicle to transport a load in the form of asecondary vehicle. When the secondary vehicle is a motorized vehiclesuch as an ATV, motorcycle, or snow mobile, the secondary vehicle may betoo heavy to be lifted onto the primary vehicle by hand.

The present invention is of particular significance when the primaryvehicle is a pickup truck and the cargo is one or more ATVs, and thepresent invention will be described herein in that context. However, thepresent invention may have application to primary vehicles other thanpickup trucks and to loads other than motorized secondary vehicles suchas an ATV.

Ramps may be used to allow a secondary vehicle to be driven onto the bedof a pickup truck. However, the bed of a pickup truck defines arelatively small useable surface area for supporting a secondaryvehicle. Accordingly, a carrier platform may be supported above the bedof the pickup truck. The carrier platform extends beyond the bed of thepickup truck to provide sufficient useable surface area for twosecondary vehicles such as ATV's to be carried in a side-by-sideorientation. Side-by-side ATV carriers require the use of a steep rampto allow onloading and offloading of the ATV's. Further, when not inuse, the side-by-side ATV carrier extends significantly beyond the sideof the pickup truck.

The need exists for improved load platforms that facilitate theonloading and offloading of loads on vehicles.

SUMMARY

The present invention may be embodied as a lift system for supportingcargo on a vehicle comprising a vehicle frame comprising a cargoplatform assembly and a displacement system. The cargo platform assemblyis configured to support the cargo. The displacement system comprises alift frame assembly, a drive system, and at least one drive linkassembly. The lift frame assembly is rigidly connected to the vehicleframe. The drive system is operatively connected to the lift frameassembly for axially rotating at least one drive axle about a drive axleaxis. The at least one drive link assembly is supported for pivotingmovement relative to the lift frame assembly about the drive axle axisand to the cargo platform assembly about a first distal axis, where theat least one drive axle is operatively connected to the at least onedrive link assembly. Operation of the drive system causes axial rotationof the at least one drive axle. Axial rotation of the at least one driveaxle causes the at least one drive link assembly to pivot about thedrive axle axis. Pivoting of the at least one drive link assembly alongthe drive axle axis displaces the cargo platform between a stowedconfiguration and a lowered configuration. The first and second distalaxes are forward of the drive axle axis when the lift system is in thestowed configuration and rearward of the drive axle axis when the liftsystem is in the lowered configuration.

The present invention may also be embodied as a method of supportingcargo on a vehicle comprising a vehicle frame comprising the followingsteps. A cargo platform assembly configured to support the cargo isprovided. A lift frame assembly is rigidly connected to the vehicleframe. A drive system is operatively connected to the lift frameassembly for axially rotating at least one drive axle about a drive axleaxis. The at least one drive axle is operatively connected to the atleast one drive link assembly for pivoting movement relative to the liftframe assembly about the drive axle axis. The at least one drive linkassembly is operatively connected to the cargo platform assembly forpivoting movement about a first distal axis. The drive system isoperated to cause axial rotation of the at least one drive axle suchthat axial rotation of the at least one drive axle causes the at leastone drive link assembly to pivot about the drive axle axis, pivoting ofthe at least one drive link assembly the drive axle axis displaces thecargo platform between a stowed configuration and a loweredconfiguration, and the first and second distal axes are forward of thedrive axle axis when the lift system is in the stowed configuration andrearward of the drive axle axis when the lift system is in the loweredconfiguration.

The present invention may also be embodied as a lift system forsupporting cargo on a vehicle comprising a vehicle frame, the liftsystem comprising a cargo platform and a displacement system. The cargoplatform assembly is configured to support the cargo and comprises amain platform assembly and at least one extension platform assemblysupported for movement between a retracted position and an extendedposition relative to the main platform assembly. The displacement systemcomprises a lift frame assembly rigidly connected to the vehicle frameand a drive system operatively connected to the lift frame assembly foraxially rotating at least one drive axle about a drive axle axis.Operation of the drive system causes axial rotation of the at least onedrive axle to displace the cargo platform between a stowed configurationand a lowered configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a first example cargo lift system ofthe present invention being used to support a load in the form of an ATVrelative to a primary vehicle in the form of a pickup truck, the firstexample cargo lift system being shown in a stowed configuration;

FIG. 2 is a side elevation view illustrating a first step in the processof loading cargo with the first example cargo lift system, the firstexample cargo lift system being shown in the stowed configuration;

FIG. 3 is a side elevation view illustrating a second step in theprocess of loading cargo with the first example cargo lift system, thefirst example cargo lift system being shown in a first intermediateconfiguration;

FIG. 4 is a side elevation view illustrating a third step in the processof loading cargo with the first example cargo lift system, the firstexample cargo lift system being shown in a second intermediateconfiguration;

FIG. 5 is a side elevation view illustrating a third step in the processof loading cargo with the first example cargo lift system, the firstexample cargo lift system being shown in a lowered configuration;

FIG. 6 is a top plan view of a portion of the primary vehicle and aportion of the first example cargo lift system;

FIG. 7 is a section view taken along lines 7-7 in FIG. 6;

FIG. 8 is a section view taken along lines 8-8 in FIG. 6;

FIG. 9 is a section view similar to FIG. 8 but with the first examplecargo lift system being shown in the lowered configuration;

FIG. 10 is a rear section view taken along lines 10-10 in FIG. 2 of theexample cargo platform assembly of the first example cargo lift system,with a first platform extension of the cargo platform assembly retractedand a second platform extension of the cargo platform assembly extended;

FIGS. 11 and 12 are rear section views of the example cargo platformassembly of the first example cargo lift system, with the first platformextension of the cargo platform assembly retracted and the secondplatform extension of the cargo platform assembly being removed;

FIG. 13 is a top plan view of the example cargo platform assembly of thefirst example cargo lift system, with the first and second platformextensions of the cargo platform assembly extended; and

FIG. 14 is a top plan view of the example cargo platform assembly of thefirst example cargo lift system, with the first and second platformextensions of the cargo platform assembly removed.

DETAILED DESCRIPTION

Referring initially to FIG. 1 of the drawing, depicted therein is afirst example cargo lift system 20 constructed in accordance with, andembodying, the principles of the present invention. The first examplecargo lift system 20 is configured to be supported by a primary vehicle22 and to support a load 24. In the example depicted in FIG. 1, theprimary vehicle 22 is a pickup truck and the load 24 is an ATV, but thefirst example lift system 20 may be used with other types of primaryvehicles and secondary vehicles.

The example primary vehicle 22 and secondary vehicle 24 are not per separt of the present invention and will be described herein only to thatextent necessary for a complete understanding of the present invention.The example primary vehicle 22 comprises a vehicle frame 30 and avehicle chassis 32. As perhaps best shown in FIG. 6, the example vehicleframe 30 defines first and second frame rails 40 and 42. The vehiclechassis defines a vehicle cab 50 and a vehicle bed 52. The examplevehicle bed 52 defines first and second bed walls 54 and 56 as perhapsbest shown in FIGS. 10-12. The example primary vehicle 22 is supportedwheels 58.

FIGS. 1-5 of the drawing illustrate that the first example cargo liftsystem 20 comprises a displacement system 60 and a cargo platformassembly 62. The example cargo lift system 20 may optionally furthercomprises a hitch jack assembly 70 for supporting the primary vehicle 22during use of the first example cargo lift system 20 to load the load 24onto and unload the load 24 from the primary vehicle 22.

As shown in FIGS. 1 and 2, the first example cargo lift system 20 may bearranged in a stowed configuration in which the cargo platform assembly62 and load 24 are supported above the bed 52 of the primary vehicle 22.Operation of the displacement system 60 is capable of displacing thecargo platform assembly 62, and the load 24 thereon, from the stowedconfiguration, through a continuum of intermediate configurations (e.g.,FIGS. 3 and 4) and into a lowered configuration as shown in FIG. 5.

In the lowered configuration, at least a portion of the cargo platformassembly 62 is in contact with the ground, and the cargo 24 may easilybe removed from the cargo platform assembly 62. In the example depictedin FIGS. 1-5, the ATV forming the load 24 may simply be driven off thecargo platform assembly 62 and onto the ground. To load the load 24 ontothe vehicle 22, the first example cargo lift system 20 is arranged inthe lowered configuration, the load 24 is arranged on the example cargoplatform assembly 62, and the displacement system 60 is operated toreconfigure the first example cargo lift system 20 from the loweredconfiguration back to the stowed configuration.

As can be seen by a comparison of FIGS. 1-5, the cargo platform assembly62 is substantially horizontal as the first example cargo lift system 20is reconfigured between the raised and lower configurations.

Referring now to FIGS. 6-9, the example displacement system 60 will nowbe described in further detail. The example displacement system 60comprises a lift frame assembly 120 and a drive system 122.

The example lift frame assembly 120 comprises first and secondconnecting assemblies 130 and 132, first and second support assemblies134 and 136, first and second brace members 140 and 142, and, if thehitch jack assembly 70 is used, a hitch receiver 144 that allows thehitch jack assembly 70 to support and stabilize the rear end of theprimary vehicle 22. The first and second connecting assemblies 130 and132 are rigidly attached to the first and second frame rails 40 and 42of the vehicle frame 30. In the example lift frame assembly 120, thefirst and second connecting assemblies 130 and 132 are detachablyattached to the first and second frame rails 40 and 42 by bolts (notshown).

The first and second brace members 140 and 142 are rigidly connected tothe first and second connecting assemblies 130 and 132 such that thefirst and second brace members 140 and 142 are rigidly supportedrelative to the frame rails 40 and 42 during normal use of the firstexample cargo lift system 20. The first and second brace members 140 and142 are rigidly connected to the first and second support assemblies 134and 136 such that the first and second support assemblies 134 and 136are also rigidly supported relative to the frame rails 40 and 42 duringnormal use of the first example cargo lift system 20.

As depicted in FIG. 6, the primary vehicle 22 defines a vehicle axis AVthat is equidistant from the first and second frame rails 40 and 42. Inthis context, lateral directions towards the vehicle axis AV are inward,and lateral directions away from the vehicle axis AV are outward.Directions toward the cab 50 from the bed 52 along the vehicle axis AVare forward, and directions away from the cab 50 towards the bed 52 arerearward. The example lift frame assembly 120 is configured such thatthe first and second support assemblies 134 and 136 are located outwardrelative to the first and second connecting assemblies 130 and 132,respectively.

The example first and second connecting assemblies 130 and 132 may bethe same but need not be identical. In the example lift frame assembly120, the example first and second connecting assemblies 130 and 132 arethe same, and only the example first connecting assembly 130 will bedescribed herein in detail with the understanding that this explanationalso applies to the example second connecting assembly 132.

FIG. 6 illustrates that the example first connecting assembly 130comprises a connecting plate 150 defining first, second, and thirdmounting tabs 152, 154, and 156 and a connector bearing assembly 158.The example connecting plate 150 is sized, configured, and dimensionedto carry the loads placed thereon during operation of the first examplecargo lift system 20 as described herein. The example mounting tabs 152,154, and 156 are integrally formed with or rigidly connected to theconnecting plate 150 to allow the connecting plate 150 to be rigidlyconnected to the first frame rail 40 by bolts extending through one ormore of the mounting tabs 152, 154, and 156. The example connectingplate 150 is further rigidly connected to the first and second bracemembers 140 and 142. The example connector bearing assembly 158 is ormay be conventional and is supported by the example connecting plate 150to support the example drive system 122 as will be described in furtherdetail below.

The example first and second support assemblies 134 and 136 may be thesame but need not be identical. In the example lift frame assembly 120,the example first and second support assemblies 134 and 136 are thesame, and only the example first support assembly 134 will be describedherein in detail with the understanding that this explanation alsoapplies to the example second support assembly 136.

In particular, the example first support assembly 134 comprises asupport plate 160 and a support bearing assembly 162. The examplesupport plate 160 is sized, configured, and dimensioned to carry theloads placed thereon during operation of the first example cargo liftsystem 20 as described herein. The example support plate 160 is furtherrigidly connected to the first and second brace members 140 and 142. Theexample support bearing assembly 162 is or may be conventional and issupported by the example support plate 160 to support the example drivesystem 122 as will be described in further detail below.

FIG. 6 further illustrates that the example drive system 122 comprises adrive frame assembly 220, an actuator system 222, first and second driveaxles 224 and 226, first and second drive link assemblies 230 and 232,and first and second stabilizer link assemblies 234 and 236. While theexample drive system 122 uses two drive axles 224 and 226, the twocoaxially aligned drive axles 224 and 226 may be replaced by a singledrive axle.

The example frame assembly 220 comprises first and second extensionmembers 240 and 242, a cross member 244, an anchor member 246, and firstand second drive bearing assemblies 250 and 252. The example actuatorsystem 222 comprises a drive cylinder 260, a drive rod 262, first andsecond drive plates 264 and 266, and a drive pin 268. The cross member244 is rigidly connected between the first and second extension members240 and 242. The first and second extension members 240 and 242 arerigidly connected to the first and second brace members 140 and 142 suchthat the anchor member 246 is rigidly supported at a desired locationrelative to the vehicle frame 30. The example anchor member 246 in turnpivotably supports the drive cylinder 260. The example drive pin 268connects the first and second drive plates 264 and 266 to the exampledrive rod 262. The example first and second drive bearing assemblies 250and 252 are supported by the first and second extension members 240 and242, respectively.

The example first and second drive link assemblies 230 and 232 may bethe same but need not be identical. In the example lift frame assembly120, the example first and second drive link assemblies 230 and 232 arethe same, and only the example first drive link assembly 230 will bedescribed herein in detail with the understanding that this explanationalso applies to the example second drive link assembly 232.

FIGS. 2 and 6 illustrate that the first and second drive link assemblies230 and 232 comprises a drive link member 270, a drive sleeve 272, adrive pin 274, and a drive link bearing assembly 276. FIG. 2 illustratesthat a notch 278 is formed in the example drive link member 270. Thedrive sleeve 272 is connected to one end of the drive link member 270,and the drive pin 274 is connected to the other end of the drive linkmember 270. The drive sleeve 272 is configured to engage the drive axle274 such that rotation of the drive axle 274 causes the drive linkmember 270 to pivot about drive axle axis AD. The drive link bearingassembly 276 is secured to a first portion of the cargo platformassembly 62 to define a first distal axis A1. The drive link member 270is thus operatively connected to the first portion of the cargo platformassembly 62 such that pivoting movement of the drive link member 270about the drive axle axis AD cause at least the first portion of thecargo platform assembly 62 (e.g., the first distal axis A1) to rotate inan arc about the drive axle axis AD.

The example first and second stabilizer link assemblies 234 and 236 maybe the same but need not be identical. In the example lift frameassembly 120, the example first and second stabilizer link assemblies234 and 236 are the same, and only the example first stabilizer linkassembly 234 will be described herein in detail with the understandingthat this explanation also applies to the example second stabilizer linkassembly 236.

FIGS. 2 and 6 illustrate that the example first and second stabilizerlink assemblies 234 and 236 comprises a stabilizer link assembly 280,first and second stabilizer pins 282 and 284, and first and secondstabilizer bearing assemblies 286 and 288. The first stabilizer bearingassemblies 286 are supported by the support plates 160 along astabilizer axis AS, and the second stabilizer bearing assemblies 288 aresupported by the cargo platform assembly 62 to define a second distalaxis A2. The first and second stabilizer pins 282 and 284 engage thefirst and second stabilizer bearing assemblies 286 and 288,respectively, such that, as the drive link member 270 pivots about thedrive axle axis AD, the stabilizer link assemblies 234 and 236 pivotabout the stabilizer axis AS. The stabilizer link assembly 280 defines apredetermined length such that, as the first portion of the cargoplatform assembly 62 at the first distal axis A1 rotates in an arc aboutthe drive axle axis AD, the stabilizer link assemblies 234 and 236 limitrotation of the cargo platform assembly 62 about the first distal axisA1. The inset in FIG. 2 illustrates that the length of the stabilizerlink assembly 280 is adjustable to allow the predetermined lengththereof to be adjusted for a particular configuration of the firstexample cargo lift system 20.

With the displacement system 60 constructed and assembled as describedabove, the example drive axles 224 and 226 engage and are supported bythe bearing assemblies 158 of the first and second connector assemblies130 and 132, by the bearing assemblies 162 of the first and secondsupport assemblies 134 and 136, and by the first and second drivebearing assemblies 250 and 252, respectively, for axial rotation aboutthe drive axle axis AD. The first and second drive plates 264 and 266are in turn connected to the drive axle 224 such that extension of thedrive rod 262 from and retraction of the drive rod 262 into the drivecylinder 260 causes axial rotation of the drive axles 224 and 226 aboutthe shaft axis AD.

With the example lift frame assembly 120 constructed and secured to theframe rails 40 and 42 as described above and the drive axle 224supported by the bearing assemblies 158, 162, 250, and 252, the exampledrive cylinder 260 and drive rod 262 are supported between the first andsecond frame rails 40 and 42. Further, the first brace member 140,second brace member 142, and drive axle 224 (and shaft axis AD definedthereby) are substantially transverse to and symmetrically arrangedabout the vehicle axis AV. The example stabilizer axis AS and distalaxes A1 and A2 are similarly transverse to the vehicle axis AV duringnormal use of the first example cargo lift system 20. The drive axleaxis AD, stabilizer axis AS, and distal axes A1 and A2 are allsubstantially parallel to each other.

As perhaps best shown in FIG. 6, the example drive link members 270 ofthe first and second drive link assemblies 230 and 232 are locatedoutwardly of the first and second side walls 54 and 56, respectively.Further, the example stabilizer link members 280 of the first and secondstabilizer link assemblies 234 and 236 are arranged outwardly from theexample drive link members 270 of the first and second drive linkassemblies 230 and 232, respectively. The notches 278 formed in thedrive link members 270 accommodate the second stabilizer pins 284 of thestabilizer link assemblies 234 and 236 when the example cargo liftsystem 20 is in its lowered position.

In addition, FIGS. 1-5 illustrate that the axes AD and AS are located tothe rear of rearmost set of wheels 58 of the vehicle 22. Axes A1 and A2are located forward of the axis AD and AS when the example cargo liftsystem 20 is in its stowed configuration as shown in FIGS. 1 and 2. Theweight of the example cargo platform assembly 62, and the load 24thereon, is carried almost exclusively by the bed 52 when the examplecargo lift system 20 is in the stowed configuration. The cargo platformassembly 62 and the axes A1 and A2 travel over the top of the axes ADand AS as the example cargo lift system 20 moves from the stowedconfiguration to the lowered configuration. In the loweredconfiguration, the axes A1 and A2 are sufficiently to the rear of thevehicle 22 that the vehicle 22 does not interfere with movement of thecargo platform assembly 62 and the load 24 carried thereon. In thelowered configuration and possibly earlier, at least a portion of thecargo platform assembly 62 and load 24 thereon is supported by theground.

Turning now to FIGS. 10-14 of the drawing, the example cargo platformassembly 62 will now be described in further detail. The example cargoplatform assembly 62 comprises a main platform 320 and first and secondextension platforms 322 and 324. The main platform 320 defines a mainwall 330, first and second side walls 332 and 334, and first and secondbearing walls 336 and 338. The first and second side walls 332 and 334define first and second spacing edges 340 and 342. First and second stopprojections 344 and 346 extend from the main wall 330. The first andsecond bearing walls 336 and 338 are configured to be supported by uppersurfaces of the first and second bed walls 54 and 56, respectively.Typically, first and second resilient pads 350 and 352 are arrangedbetween the bearing walls 336 and 338 and the bed walls 54 and 56,respectively.

The example first and second extension platforms 322 and 324 may be thesame but need not be identical. In the example lift frame assembly 120,the example first and second extension platforms 322 and 324 are thesame, and only the example first extension platforms 322 will bedescribed herein in detail with the understanding that this explanationalso applies to the example second extension platform 324.

The example extension platform 322 comprises an extension member 360, atleast one extension guide 362, and at least one lock pin 364. Theexample extension member 360 defines an extension wall 370, an outerwall 372, a return wall 374, and at least one lock flange 376. A flangeopening 378 is formed in each lock flange 376. The at least oneextension guide 362 defines an upper surface 380, a guide tip 382, a tipsurface 384, and first and second lock openings 386 and 388.

The extension platforms 322 and 324 are movably supported by the mainplatform 320 to allow an overall width of the example cargo platformassembly 62 to be adjusted.

In particular, the first and second side walls 332 and 334 define firstand second guide openings 390 and 392, respectively. The guide openingsreceive the extension guides 362 of the first and second extensionplatforms 322 and 324, respectively. Displacing the extension platforms322 and 324 fully inwardly extends the guide tips 382 past the stopprojections 344 and 346 (see, e.g., the left side of FIGS. 10-12) toplace the extension platforms 322 and 324 in a retracted positionrelative to the main platform 320. The lock pins 364 may be insertedthrough the aligned holes 378 and 388 to secure the extension platforms322 and 324 in their retracted configurations.

Displacing the extension platforms 322 and 324 outwardly until the tipsurfaces 384 of the guide tips 382 engage the stop projections 344 and346 (see, e.g., the right side of FIG. 10) places the extensionplatforms 322 and 324 in an extended position relative to the mainplatform 320. The lock pins 364 may be inserted through the alignedholes 378 and 388 to secure the extension platforms 322 and 324 in theirextended configurations.

The extension platforms 322 and 324 may be removed from the mainplatform 320 by tilting the extension platforms 322 and 324 such thatthe guide tips 382 can clear the stop projections (see, e.g., right sideof FIGS. 11 and 12) and then pulling the extension platforms 322 and 324out until the extension guides 362 are removed from the guide openings390 and 392 (see, e.g., right side of FIG. 12). FIG. 13 illustrates thesurface area of the cargo platform assembly 62 with the first and secondextension platforms 322 and 324 extended, and FIG. 14 illustrates thesurface area of the cargo platform assembly 62 with both extensionplatforms 322 and 324 removed.

What is claimed is:
 1. A displacement system for displacing a cargoplatform for supporting cargo relative to a vehicle defining a forwarddirection and comprising a vehicle frame comprising first and secondframe rails, the displacement system comprising: a lift frame assemblyadapted to be supported by the vehicle frame; at least one drive axlesupported by the lift frame assembly; at least one drive plateoperatively connected to the at least one drive axle; at least one drivelink operatively connected to the at least one drive axle and adapted tobe operatively connected to the cargo platform; at least one actuatorsystem comprising a drive cylinder and a drive shaft, where the drivecylinder is pivotably attached to one of the lift frame assembly and theat least one drive plate, the drive shaft is pivotably attached to oneof the lift frame assembly and the at least one drive plate, andoperation of the actuator system displaces the at least one drive plate;whereby displacement of the at least one drive plate causes axialrotation of the drive axle; axial rotation of the drive axle displacesthe at least one drive link between first and second drive linkpositions; and with the lift frame assembly supported by the vehicleframe and the at least one drive link operatively connected to the cargoplatform, displacement of the at least one drive link between the firstand second drive link positions displaces the cargo platform betweenfirst and second cargo platform positions.
 2. A displacement system asrecited in claim 1, in which at least one stabilizer link is supportedby the lift frame assembly and adapted to be connected to the cargoplatform, where the at least one stabilizer link is configured tostabilize the cargo platform as the cargo platform moves between firstand second cargo platform positions.
 3. A displacement system as recitedin claim 1, in which the actuator system is supported between the firstand second frame rails.
 4. A displacement system as recited in claim 1,in which the actuator system is supported in the forward directionrelative to the drive shaft.
 5. A displacement system as recited inclaim 1, in which the actuator system is supported between the first andsecond frame rails and in the forward direction relative to the driveshaft.
 6. A displacement system as recited in claim 1, in which the liftframe assembly comprises at least one frame bearing assembly for axiallysupporting the drive axle.
 7. A displacement system as recited in claim1, in which the lift frame assembly comprises at least one drive bearingassembly for axially supporting the drive axle.
 8. A displacement systemas recited in claim 1, in which the lift frame assembly comprises: atleast one frame bearing assembly for axially supporting the drive axle;and at least one drive bearing assembly for axially supporting the driveaxle.
 9. A displacement system as recited in claim 1, in which a singledrive axle is supported by the lift frame assembly.
 10. A displacementsystem as recited in claim 1, in which first and second drive axles aresupported by the lift frame assembly.
 11. A displacement system fordisplacing a cargo platform for supporting cargo relative to a vehicledefining a forward direction and comprising a vehicle frame comprisingfirst and second frame rails, the displacement system comprising: a liftframe assembly adapted to be supported by the vehicle frame; at leastone drive axle supported by the lift frame assembly; at least one driveplate operatively connected to the at least one drive axle; first andsecond drive links operatively connected to the at least one drive axleand adapted to be operatively connected to the cargo platform; at leastone actuator system comprising a drive cylinder and a drive shaft, wherethe drive cylinder is pivotably attached to the lift frame assembly orthe at least one drive plate, the drive shaft is pivotably attached tothe lift frame assembly or the at least one drive plate, and operationof the actuator system displaces the at least one drive plate; wherebydisplacement of the at least one drive plate causes axial rotation ofthe drive axle; axial rotation of the drive axle displaces the first andsecond drive links between first and second drive link positions; andwith the lift frame assembly supported by the vehicle frame and the atfirst and second drive links operatively connected to the cargoplatform, displacement of the first and second drive links between thefirst and second drive link positions displaces the cargo platformbetween first and second cargo platform positions.
 12. A displacementsystem as recited in claim 11, in which first and second stabilizerlinks are supported by the lift frame assembly and adapted to beconnected to the cargo platform, where the first and second stabilizerlinks are configured to stabilize the cargo platform as the cargoplatform moves between first and second cargo platform positions.
 13. Adisplacement system as recited in claim 11, in which the actuator systemis supported between the first and second frame rails and in the forwarddirection relative to the drive shaft.
 14. A displacement system asrecited in claim 11, in which the lift frame assembly comprises: firstand second frame bearing assemblies for axially supporting the driveaxle; and first and second drive bearing assemblies for axiallysupporting the drive axle.
 15. A displacement system as recited in claim11, in which a single drive axle is supported by the lift frameassembly.
 16. A displacement system as recited in claim 11, in whichfirst and second drive axles are supported by the lift frame assembly.17. A displacement system as recited in claim 16, in which first andsecond drive plates are operatively connected to the first and seconddrive axles, respectively.
 18. A method of displacing a cargo platformfor supporting cargo relative to a vehicle defining a forward directionand comprising a vehicle frame comprising first and second frame rails,the method comprising the steps of: providing a lift frame assemblyadapted to be supported by the vehicle frame; supporting at least onedrive axle with the lift frame assembly; operatively connecting at leastone drive plate to the at least one drive axle; operatively connectingat least one drive link to the at least one drive axle, where the atleast one drive link is adapted to be operatively connected to the cargoplatform; providing at least one actuator system comprising a drivecylinder and a drive shaft; pivotably attaching the drive cylinder toone of the lift frame assembly and the at least one drive plate;pivotably attaching the drive shaft to one of the lift frame assemblyand the at least one drive plate; operating the actuator system todisplace the at least one drive plate, where displacement of the atleast one drive plate causes axial rotation of the drive axle, axialrotation of the drive axle displaces the at least one drive link betweenfirst and second drive link positions, and with the lift frame assemblysupported by the vehicle frame and the at least one drive linkoperatively connected to the cargo platform, displacement of the atleast one drive link between the first and second drive link positionsdisplaces the cargo platform between first and second cargo platformpositions.
 19. A method as recited in claim 18, further comprising thestep of supporting at least one stabilizer link by the lift frameassembly, where the at least one stabilizer link is adapted to beconnected to the cargo platform such that the at least one stabilizerlink stabilizes the cargo platform as the cargo platform moves betweenfirst and second cargo platform positions.
 20. A method as recited inclaim 18, in which the lift frame assembly supports first and seconddrive axles.